Spectral and statistical analysis for ferroresonance phenomenon in electric power systems

This study presents our findings on the ferroresonance phenomenon for the Seyitomer?CIsiklar part of the Electric Power System of 380?kV in Turkey. In this context, the power spectral density approach and Short-Time Fourier Transforms are applied to the voltage variations for phase R of the sample power network. The findings show that the ferroresonance event can be represented by the interharmonics between 50 and 250?Hz, as well as statistical properties. In addition, a histogram of the ferroresonance region shows a different characteristic from the overall data and the non-ferroresonance region. This different characteristic can be defined by an asymmetrical distribution characteristic, and its numerical measure is given by the ??Noise to Signal Ratio?? of 0.624.     

High-fidelity simulations of unsteady flow through turbopumps and flowliners

High-fidelity computations were carried out to analyze the orbiter liquid hydrogen (LH₂) feedline flowliner and the low-pressure-fuel-turbopump (LPFTP). Computations were performed on the Columbia platform which is a 10,240-processor supercluster consisting of 20 Altix nodes with 512 processors each. Various computational models were used to characterize the unsteady flow features in the turbopump, including the orbiter LPFTP inducer, the orbiter manifold and an experimental test article used to represent the manifold. Unsteady flow originating from the orbiter LPFTP inducer is one of the major contributors to the high-frequency cyclic loading that results in high cycle fatigue damage to the gimbal flowliners just upstream of the LPFTP. The flowfields for the orbiter manifold and representative test article are computed and analyzed for similarities and differences. An incompressible Navier–Stokes flow solver INS3D, based on the artificial compressibility method, was used to compute the flow of liquid hydrogen in each test article.     

Combination of culture-dependent and culture-independent molecular methods for the determination of lactic microbiota in sucuk

In this study, the culture-dependent and culture-independent molecular methods were used for the identification of lactic acid bacteria (LAB) in sucuk a Turkish fermented dry sausage. On the one hand, the PCR-DGGE method targetting the V1 and V3 regions of 16S DNA was applied to DNA that was directly extracted from sucuk samples. On the other hand, rep-PCR fingerprinting was performed for the primary differentiation and grouping of the isolates, and the results were confirmed by sequencing of the 16S rDNA and 16S-23S rDNA intergenic spacer region. As a result of the PCR-DGGE analysis of all the samples, total 8 different lactic acid bacteria were identified, and Lactobacillus sakei, Lactobacillus curvatus and Weissella viridescens were the dominant microbiota among these bacteria. The culture-dependent approach indicated that the majority of the strains belonged to the Lactobacillus genera including Lb. sakei, Lactobacillus plantarum, Lb. curvatus, Lactobacillus brevis, Lactobacillus farciminis and Lactobacillus alimentarius. However, Leuconostoc and Weisella were also detected as minor genera. Again, Lactococcus piscium, Weissella halotolerans, Staphylococcus succinus and the comigrated Staphylococcus piscifermentans/Staphylococcus condimenti/Staphylococcus carnosus group were detected only with the culture-independent method while Lb. plantarum, Leuconostoc mesenteroides and Leuconostoc citreum were identified only by using the culture-dependent method. In the results, it was concluded that the combination of culture-dependent and culture-independent methods was necessary for reliable and detailed investigation of LAB communities in fermented food products.     

Entropy-functional-based online adaptive decision fusion framework with application to wildfire detection in video

In this paper, an entropy-functional-based online adaptive decision fusion (EADF) framework is developed for image analysis and computer vision applications. In this framework, it is assumed that the compound algorithm consists of several subalgorithms, each of which yields its own decision as a real number centered around zero, representing the confidence level of that particular subalgorithm. Decision values are linearly combined with weights that are updated online according to an active fusion method based on performing entropic projections onto convex sets describing subalgorithms. It is assumed that there is an oracle, who is usually a human operator, providing feedback to the decision fusion method. A video-based wildfire detection system was developed to evaluate the performance of the decision fusion algorithm. In this case, image data arrive sequentially, and the oracle is the security guard of the forest lookout tower, verifying the decision of the combined algorithm. The simulation results are presented.     

Suitability of acid whey for fermented and fresh-pack cornichon pickle production

Suitability of acid whey (AW) as brine media in fermented and fresh-pack cornichon pickle production was investigated. Fermented and fresh-pack pickles were produced with AW and vinegar (control). Microbiological, textural, colour and sensory properties of the pickles were monitored during 12-wk storage at room temperature. Fermented and fresh-pack pickles manufactured with AW exhibited higher total solids content than the pickles manufactured with vinegar. Acid whey as pickling media increased the development of presumptive lactococci species both in fermented and in fresh-pack pickles. This study shows that AW is a suitable pickling media for fermented and fresh-pack cornichon pickle manufacture.     

Synthesis and Properties of Boron Doped NaxCo2O4 Nanocrystalline Ceramics

Sodium cobalt oxide (NaCo₂O₄) nanofibers with diameters ranging between 20 and 200?nm were prepared by electrospinning a precursor mixture of PVA/(Na–Co) acetate. This was the first time any such attempt was made. Afterwards, the electrospun nanofibers were subjected to calcination treatment. The characteristics of the fibers were investigated using a Fourier transform infrared spectroscopy, a X-ray diffractometer, and a scanning electron microscopy. The boron doped and undoped NaCo₂O₄ nanofibers calcined at 850?°C were polycrystalline of the γ Na_xCo₂O₄ phase having diameters ranging between 20 and 60?nm with grain sizes of 5–10?nm, and the nanofibers calcined at 800?°C were single crystals having linked particles or crystallites with particle sizes ranging between 60 and 200?nm. The results indicated a significant effect of calcination temperature on the crystalline phase and morphology of the nanofibers. It could be seen in the SEM micrograph of the fibers that when boron was added, this resulted in the formation of cross-linked bright-surfaced fibers. The average fiber diameter for boron doped and undoped fiber mats were 204 and 123?nm, respectively. The grain diameters of boron doped and undoped nanocrystalline sintered powders were measured as 140 and 118?nm, respectively.     

Natural radioactivity levels of granites used in Turkey

Thirty granite samples commonly used in Turkey were surveyed for natural radioactivity. Concentrations of natural radionuclides in all samples were determined by gamma-ray spectroscopy with hyper-pure germanium detector. The activity concentrations measured for (226)Ra and (232)Th ranged from 0.7±0.1 to 186±1 Bq kg(-1), and from 0.5±0.1 to 249±2 Bq kg(-1), respectively. The activity concentrations obtained for (40)K varied from minimum detectable activity (0.4 Bq kg(-1)) to 1935±11 Bq kg(-1). The radium equivalent activity (Ra(eq)), the absorbed dose rate (D), the external hazard index (H(ex)) and the annual effective dose equivalent were also calculated and compared with the international recommended values. Granite samples were also analysed mineralogically. It was observed that the presence of large amount orthoclase and radiogenic accessory minerals are the sources of high activity concentration levels.